The present invention relates in general to fluid filtration devices that are constructed and arranged to filter an incoming fluid prior to utilization of that fluid downstream from the filtration site. More specifically, the present invention relates to a fuel filter that includes a centerpost assembly and a replaceable filter cartridge that slides onto the centerpost assembly. One focus of the present invention is the concept of preventing fuel delivery to the engine if a “proper” filter cartridge is not installed on the centerpost assembly. In the context of the present invention, the term “proper” is used to describe a filter cartridge that is approved for use by the original equipment manufacturer. It is important that the replacement filter cartridge maintain design compatibility so that it fits properly and is properly sealed around the centerpost assembly.
In a more generic sense, the concept of “no filter-no run” means that if a filter cartridge is not installed, there is no appreciable flow of fuel to the engine. While the present invention provides this type of structure by its design of a “proper” filter cartridge, the specifics of the centerpost assembly and filter cartridge construction are important. One beneficial feature of the present invention is that its selected construction for this flow-control feature is not restrictive to the flow of fuel. If the selected construction for the flow-control feature were to introduce too much restriction, this could cause fuel system problems or inefficiencies.
Any prior art filter structures that try to address the desire for a “no filter-no run” design are considered to have various disadvantages. For example, the resulting structures are typically either too complicated, too hard to service, too costly, or have a flow-control valve construction that is too restrictive to the fuel flow. Another design disadvantage of earlier designs is that typically whatever mechanism is utilized to open a closed valve, there is a mechanical interaction which simply introduces additional design complexity and the potential for failure. The present invention provides a novel and unobvious structure to create a “no filter-no run” fuel filter structure that overcomes many of the disadvantages with earlier designs.